Vermont Symbols, Soil: Tunbridge Soil Series

Adopted on March 27, 1985.

No. 9 of the Acts of 1985, effective March 27, 1985, designated the Tunbridge Soil Series as the official State Soil. The Tunbridge series (course-loamy, mixed, frigid Typic Haplothrod) consists of moderately deep to bedrock, well drained soils. It was selected from among more than 160 different soil series in the state. As it is a typical "hill farm" and "sugarbush" soil, the Tunbridge series well represents the soil resources of Vermont. A soil formed in loamy glacial till, it has good potential for agriculture and forestry. As Professor Richmond Bartlett of UVM says, "It's the soil that makes Vermont hills greener than those either in New Hampshire or New York."

The Tunbridge series consists of loamy, well-drained soils that formed in Wisconsin-age glacial till. These soils are 20 to 40 inches deep over schist, gneiss, phyllite, or granite bedrock. They occur extensively in mountainous areas of Vermont, in all but one county. The Tunbridge series became the third official State soil in the country in March 1985. The series was named after the town of Tunbridge, Orange County, Vermont.

It was designated the official state soil by the Vermont Legislature in March 1985. It was selected from among more than 160 different soil series in the state. As it is a typical "hill farm" and "sugarbush" soil, the Tunbridge series well represents the soil resources of Vermont. A soil formed in loamy glacial till, it has good potential for agriculture and forestry. As Professor Richmond Bartlett of UVM says, "It's the soil that makes Vermont hills greener than those either in New Hampshire or New York."

Tunbridge soils are used mainly for woodland. White ash, American beech, white birch, yellow birch, hemlock, white pine, red spruce, red maple, and sugar maple are typical species. Sugar maple is especially important; Vermont produces the largest amount of maple syrup in the U.S. Some areas have been cleared and are used for hay and pasture. Recreational uses are common on these soils. They include trails for hiking, mountain biking, snowmobiling, and skiing
 

TAXONOMIC CLASS: Coarse-loamy, isotic, frigid Typic Haplorthods

TYPICAL PEDON: Tunbridge fine sandy loam, on a south-facing slope of 4 percent, in a rocky wooded area. (Colors are for moist soil.)

A--0 to 2 inches; dark brown (7.5YR 3/2) fine sandy loam; weak fine granular structure; very friable; many roots; 5 percent rock fragments; extremely acid; abrupt wavy boundary. (0 to 6 inches thick)

E--2 to 3 inches; grayish brown (10YR 5/2) fine sandy loam; weak fine granular structure, friable; many roots; 5 percent rock fragments; very strongly acid; abrupt broken boundary. (0 to 4 inches thick)

Bh--3 to 9 inches; dark reddish brown (5YR 3/4) loam; moderate medium angular blocky structure; friable; many roots; 10 percent rock fragments; very strongly acid; clear wavy boundary. (0 to 4 inches thick)

Bs--9 to 14 inches; yellowish brown (10YR 5/6) silt loam; weak medium subangular blocky structure; friable; many roots; 10 percent rock fragments; very strongly acid; clear wavy boundary. (0 to 16 inches thick.)

C--14 to 28 inches; dark grayish brown (2.5Y 4/2) gravelly fine sandy loam; massive; friable; common roots; 15 percent rock fragments; moderately acid; abrupt irregular boundary. (0 to 16 inches thick)

R--28 inches; mica schist and gneiss bedrock.

TYPE LOCATION: Lamoille County, Vermont; Town of Stowe; 0.25 mile east of Town Road #23 and 2.50 miles north of junction of Town Road #23 and Vermont Route 108; approximate latitude 44 degrees, 31 minutes, 00 seconds N., longitude 72 degrees, 42 minutes, 00 seconds W., NAD 27.

RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 14 to 38 inches. The depth to bedrock ranges from 20 to 40 inches. Reaction ranges from extremely acid through moderately acid in the solum and from strongly acid through slightly acid in the substratum. Rock fragments are mostly gravel, channers, and cobbles and range from 5 to 35 percent throughout the soil. The thickness of spodic horizon (Bh, Bs, and Bhs horizon, where present) ranges from 4 to 16 inches and is weakly smeary or not smeary. The silt content in the solum and substratum is typically less than 50 percent. The fine-earth is typically fine sandy loam, sandy loam, very fine sandy loam or loam, but horizons of silt loam are allowed. Stony and bouldery phases of the Tunbridge series are recognized.

Some pedons have Oi, Oe, and/or Oa horizons overlying the A horizon. Combined thickness of the O horizons is 0 to 5 inches thick.

The A horizon is neutral or has hue of 5YR to 10YR, value of 2 to 5, and chroma of 0 to 4. It is typically loam, very fine sandy loam, fine sandy loam or sandy loam in the fine-earth fraction but includes silt loam.

Some pedons have an Ap horizon that has hue of 5YR to 10YR, value of 2 to 4, and chroma of 2 to 4. Textures are similar to the A horizon.

The E horizon has hue of 5YR to 10YR, value of 4 to 6, and chroma of 1 or 2. It is typically loam, very fine sandy loam, fine sandy loam, sandy loam or loamy fine sand in the fine-earth fraction but includes loamy fine sand and silt loam.

Some pedons have a BE horizon that has hue of 5YR to 10YR, value of 4 to 6, and chroma of 2 to 4. Textures are similar to the E horizon.

The Bh horizon, where present, is neutral or has hue of 5YR to 10YR. It typically has value of 2 or 3, and chroma of 0 to 2, but higher values and chromas are allowed.

The Bs horizon, where present, has hue of 5YR to 2.5Y, value and chroma of 4 or more.

Some pedons have a Bhs horizon that has hue of 5YR to 10YR, value and chroma of 3 or less. It is less than 4 inches thick.

Some pedons have a BC horizon with hue of 7.5YR to 2.5Y, value of 3 to 5, and chroma of 3 to 8. It is up to 12 inches thick.

The B horizons are typically loam, very fine sandy loam, fine sandy loam or sandy loam in the fine-earth fraction but includes silt loam.

The C horizon has hue of 10YR to 5Y, value of 4 to 6, and chroma of 2 to 6. It is typically loam, very fine sandy loam, fine sandy loam, or sandy loam in the fine-earth fraction but includes silt loam.

Bedrock is slightly weathered schist, gneiss, phyllite, or granite.

COMPETING SERIES: These are the Bangor, Battydoe, Berkshire, Chatham, Dekapen, Dixfield, Elliottsville, Groveton, Houghtonville, Lombard(T), Michigamme, Onota, Penquis, Potsdam, Rawsonville, Revel, and Welcome series. Bangor, Battydoe, Berkshire, Chatham, Dekapen, Groveton, Houghtonville, Lombard(T), and Potsdam soils have bedrock greater than 40 inches below the soil surface. Elliottsville soils have more clay in the particle-size control section. Michigamme soils formed in eolian material over glacial till. Onota, Revel and Welcome soils have sandstone bedrock. Penquis soils have more silt and crushable rock fragments throughout the soil. Rawsonville soils have a spodic horizon more than 16 inches thick or a Bh horizon more than 4 inches thick.

GEOGRAPHIC SETTING: Tunbridge soils are on nearly level to very steep glaciated uplands. They are on mountain side slopes, mountain tops, mountain ridges, hill tops, and hill slopes. Slope ranges from 0 to 75 percent. The soils formed in loamy glacial till of Wisconsin age derived mainly from micaceous schist, gneiss, and phyllite. Mean annual precipitation ranges from about 30 to 50 inches, and the mean annual temperature ranges from 38 to 46 degrees F. The frost-free season ranges from 60 to 160 days. Elevations range from 5 to 2500 feet above mean sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Berkshire, Houghtonville, Lyman, Rawsonville, Marlow, Peru, and Sunapee soils. The very deep Berkshire, Houghtonville, and Marlow soils are on similar landscapes as the Tunbridge soils. Marlow soils have a dense substratum. Houghtonville soils have a thicker spodic horizon. Lyman soils are shallow. The very deep, moderately well drained Peru and Sunapee soils are in slightly lower positions on the landscape, and Peru soils have a dense substratum. The moderately deep Rawsonville soils are on similar landscapes as the Tunbridge soil and have a thicker spodic horizon.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate or moderately rapid.

USE AND VEGETATION: Most areas are wooded. The common trees are American beech, white ash, yellow birch, paper birch, northern red oak, sugar maple, eastern white pine, hemlock, red spruce, white spruce, and balsam fir. A few areas have been cleared and are primarily used for hay and pasture. Some cleared areas are used for cultivated crops.

DISTRIBUTION AND EXTENT: Vermont, Maine, Massachusetts, New Hampshire, and New York; MLRAs 143, 144A, and 144B. The series is extensive.

MLRA OFFICE RESPONSIBLE: Amherst, Massachusetts.

SERIES ESTABLISHED: Orange County, Vermont, 1975.

REMARKS: 1. Tunbridge is the official "State Soil of Vermont."

2. Albic horizon extends horizontally through 50 percent or more of each pedon. Albic horizons are often hard to locate because tree throws and other disturbances have destroyed the albic horizons in many areas of Tunbridge soils. Albic horizons are often thin, may be discontinuous, and located within 4 inches of the soil surface.

3. The diagnostic horizons and features recognized in this pedon are:

a. Ochric epipedon - the zone from 0 to 3 inches (A and E horizons).

b. Spodic horizon - the zone from 3 to 9 inches (Bh horizon).

ADDITIONAL DATA: NSSL lab data is available for the following pedons: S74VT-17-9, S74VT-17-15, S76VT-15-10, S78VT-25-5.

Soil Interpretation Record Numbers for the Tunbridge Series are: Tunbridge, VT0029; Tunbridge, stony, VT0075; and Tunbridge, bouldery, VT0113.

National Cooperative Soil Survey
U.S.A.